Good to know of the unstable branch's presence, I'll see to getting onto testing that out in due time. In the meantime, here's more notes from playing earlier today, primarily while... well, achievement hunting. Or testing, specifically.

* Clipping through the walls and out of bounds is happening the more I notice it. On the sharp right-hander off of a raised section of track near the start of Ackinovae, it's too possible to phase straight through the solid wall to the left.
* The same can be said for Survival Mode, where beyond Zone 30, grinding along the outside of the long, wide corners in Harpstone would often make the ship fall right through without taking any damage.
* Speaking of Survival Mode, I suspect that triggering the Rescue Drone currently does not count as imperfecting the current Zone. It also doesn't cost any Shield Energy.
* Possibly disable weather effects and crowd sounds when playing Survival Mode?
* The AI on Maceno Bay is still noticeably more difficult to defeat than any other track in the primary lineup.
* The new Ishtar Citadel layout is fantastic, though the Start/Finish line might want to be shifted a bit further up alongside the Pit Lane.
* In trying over and over to get some of the specific Elimination achievements, on one restart, the game wasn't playing any ship thruster sounds at all. Pausing and unpausing the game corrected it.
* Also during these, there were several races where the specific craft that required elimination wasn't in the race at all. Possibly the game is putting two of the same team in the race?
* Still considering the possibility of preventing collecting identical pickups in sequence.
* Regarding Missiles, the increased lock-on speed when firing backwards is probably too fast now? Also I don't remember if Missiles could be dumbfired backwards in Fusion or not.
* The Crowd Pleaser achievement did not trigger during the Season 3 race on Maceno Bay. I had managed to get three Eliminations via Plasma and a fourth with the Cannon of all things.
* The Lucky Shot achievement for getting 15 cumulative Plasma kills only appeared at the end of the race, not on the 15th elimination. This could possibly have some unwanted effects should the race be restarted or retired from before it is finished.